The subject matter described herein relates generally to electric generators, and more specifically, to methods, systems, and apparatus that enable a switch-mode power supply to have a dual primary transformer that derives a low voltage power supply from two different power sources of disparate voltage ratings.
A switched-mode power supply (SMPS) is an electronic power supply that incorporates a switching regulator to convert electrical power efficiently. Like other power supplies, an SMPS transfers power from a source, like mains power, to a load while converting voltage and current characteristics. An SMPS is usually employed to efficiently provide a regulated output voltage, typically at a level different from an input voltage.
Electronic voltage regulators are used to regulate the output voltage of a brushless synchronous generator by controlling the level of current in an exciter field of the generator. The power source for the excitation is most often derived from a relatively small permanent magnet generator (PMG) that is part of a larger, main generator. However, because a rotor of the PMG is mounted to the same shaft as a rotor of the main generator, it is required that a prime mover of the main generator be rotating in order for the electronic voltage regulator to receive input power. As such, if the prime mover of the main generator is not rotating, the electronic voltage regulator module is unable to perform system monitoring (e.g., temperature monitoring) or perform communication with other system elements because power is not being supplied to the electronic voltage regulator. Thus, the electronic voltage regulator module cannot perform system monitoring nor communication functions until the prime mover begins rotating and power is once again provided to the electronic voltage regulator.